An important function of the lung is the transport of material from the respiratory airways to the pharynx. The role of ciliary activity in this transport has been validated experimentally both in vitro and in vivo. However, a direct method that can be eventually implemented for clinical use to measure frequency of ciliary beat in situ has not been developed. During the last two years we have developed and validated a unique method to precisely measure frequency of ciliary beat using laser light scattering spectroscopy. This project is intended to undertake the development, evaluation and fabrication of a fiber optic laser spectrometer-bronchoscope to objectively and reliably measure frequency of ciliary beat in the lung in situ. Suppported by this grant we will also continue our in vitro studies on the ionic and hormonal regulation of respiratory ciliary activity using laser scattering spectroscopy.